PT - JOURNAL ARTICLE ED - , TI - Correction AID - 10.1136/bmjopen-2015-008808corr1 DP - 2015 Sep 01 TA - BMJ Open PG - e008808 VI - 5 IP - 9 4099 - http://bmjopen.bmj.com/content/5/9/e008808.short 4100 - http://bmjopen.bmj.com/content/5/9/e008808.full SO - BMJ Open2015 Sep 01; 5